Composite structures (or components) are generally made from two or more constituent materials with significantly different physical or chemical properties. When combined, they produce a structure with characteristics different from the individual materials, with the aim of using the benefit of both.
When manufacturing composite structures using a manufacturing process such as Automated Fiber Placement (AFP) or Automated Tape Layering (ATL), inspecting the dimensional requirements of the manufactured structures is an important part of the manufacturing process. At least part of the inspection process is done on freshly laid fiber. It is very difficult to obtain high quality images from such surfaces due to the different directional reflectivity of the fibers. In addition, the features to be inspected are black details on black background, thus producing poor contrast.
For these reasons, known methods for performing dimensional inspection involve gathering data via manual inspection using a hand-held laser tracker, and having an operator compare the measured data with theoretical data from a Computer-Aided Design (CAD) file. In the case of a composite structure having many plies, manual inspection of the fibers of each ply of the structure is extremely time consuming. Another shortcoming of manual inspection is that it is dependent on the hand and eye skills of the operator, which makes it harder to validate the inspection at a later time.
There is therefore a need to improve the inspection phase of the manufacturing process for certain structures.